John Adams comes into focus first as a man made of sentences—short, vigorous, argumentative—and only then as a public officer stitched to a perilous decade. He was not a figure of placid charisma. He had a lawyer’s appetite for the exact word, a farmer’s suspicion of fashionable nonsense, and a temperament that took offense more quickly than it forgave. But running beneath the volatility was the harder discipline of a New England conscience: the belief that law is a lamp in bad weather and that republics survive by habits long after they have forgotten the speeches that justified them. If George Washington invented the posture of the executive, Adams tested whether the posture could survive storm. He did so as a second son in every sense—the second president of a fragile frame, the second idol in a pantheon that only reluctantly includes men who  ...